They have different registrars.
For www.onedesignphotos.com I registered ns1 and ns2 with my registrar and they seem to reply fine.

In another country one friend can access the domain and the other cannot.

On dnsstuff I got this report:

FAIL No NS A records at nameservers WARNING: Your nameservers do not include any corresponding A records when asked for your NS records. They probably are not returning the A records when asked, which can prevent some other DNS servers from contacting your DNS servers. They should do this if they are authoritative for those A records (in BIND, you should not use 'minimal-responses yes;'). The problem record(s) are:

Nameserver 88.151.81.26 did not provide any IPs
Nameserver 88.151.81.26 did not provide any IPs